From 1669a71fd8a4bd570f09fc2df67279d6936cc5ad Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Fri, 22 Jun 2018 19:00:03 +0200 Subject: [PATCH 15/21] migration: Don't activate block devices if using -S RH-Author: Dr. David Alan Gilbert Message-id: <20180801135522.11658-17-dgilbert@redhat.com> Patchwork-id: 81576 O-Subject: [qemu-kvm RHEL8/virt212 PATCH 16/18] migration: Don't activate block devices if using -S Bugzilla: 1594384 RH-Acked-by: Peter Xu RH-Acked-by: John Snow RH-Acked-by: Juan Quintela From: "Dr. David Alan Gilbert" Activating the block devices causes the locks to be taken on the backing file. If we're running with -S and the destination libvirt hasn't started the destination with 'cont', it's expecting the locks are still untaken. Don't activate the block devices if we're not going to autostart the VM; 'cont' already will do that anyway. This change is tied to the new migration capability 'late-block-activate' that defaults to off, keeping the old behaviour by default. bz: https://bugzilla.redhat.com/show_bug.cgi?id=1560854 Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela (cherry picked from commit 0f073f44df109ea0910d67caede70dec95956ff6) --- migration/migration.c | 34 +++++++++++++++++++++++++++------- qapi/migration.json | 5 ++++- 2 files changed, 31 insertions(+), 8 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index b6294f6..edf1c06 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -199,6 +199,16 @@ static void migrate_generate_event(int new_state) } } +static bool migrate_late_block_activate(void) +{ + MigrationState *s; + + s = migrate_get_current(); + + return s->enabled_capabilities[ + MIGRATION_CAPABILITY_LATE_BLOCK_ACTIVATE]; +} + /* * Called on -incoming with a defer: uri. * The migration can be started later after any parameters have been @@ -308,13 +318,23 @@ static void process_incoming_migration_bh(void *opaque) Error *local_err = NULL; MigrationIncomingState *mis = opaque; - /* Make sure all file formats flush their mutable metadata. - * If we get an error here, just don't restart the VM yet. */ - bdrv_invalidate_cache_all(&local_err); - if (local_err) { - error_report_err(local_err); - local_err = NULL; - autostart = false; + /* If capability late_block_activate is set: + * Only fire up the block code now if we're going to restart the + * VM, else 'cont' will do it. + * This causes file locking to happen; so we don't want it to happen + * unless we really are starting the VM. + */ + if (!migrate_late_block_activate() || + (autostart && (!global_state_received() || + global_state_get_runstate() == RUN_STATE_RUNNING))) { + /* Make sure all file formats flush their mutable metadata. + * If we get an error here, just don't restart the VM yet. */ + bdrv_invalidate_cache_all(&local_err); + if (local_err) { + error_report_err(local_err); + local_err = NULL; + autostart = false; + } } /* diff --git a/qapi/migration.json b/qapi/migration.json index 9d0bf82..618d2de 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -357,13 +357,16 @@ # @dirty-bitmaps: If enabled, QEMU will migrate named dirty bitmaps. # (since 2.12) # +# @late-block-activate: If enabled, the destination will not activate block +# devices (and thus take locks) immediately at the end of migration. +# (since 3.0) # Since: 1.2 ## { 'enum': 'MigrationCapability', 'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks', 'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram', 'block', 'return-path', 'pause-before-switchover', 'x-multifd', - 'dirty-bitmaps' ] } + 'dirty-bitmaps', 'late-block-activate' ] } ## # @MigrationCapabilityStatus: -- 1.8.3.1